aka_eli8:

Firstly, they do not enforce their community use guidelines whatsoever, and consequently there is absolutely no oversight of artwork. You can upload artwork that says I RAPED YOUR MOM and CafePress will happily print it for you on any of 33 different products. If enough people complain, your products might be removed, but someone else can upload the exact same thing a week later.
Previously removed products have included shirts that say It’s only rape if she says no, so gag the bitch, and infant onesies that say Can’t rape the willing!

Secondly, they use American Apparel materials, and you already know how we feel about them.
Thirdly, they allow customers to pirate other artists’ work.
Finally, the quality of their printing sucks also. It’s like an iron-on patch.